Energy balance with Battery backup

[solarysnrg]

In a system connected to the grid with backup batteries, the energy balances are not consistent!

EDirUse+EBatCh+E_Grid > E_Avail ( much greater )

[Bruno Wittmer]

The variable EDirUse containds already E_Grid. It represents all the energy that does not go through the storage:

E_Avail = EDirUse + EBatCh

[solarysnrg]

The variable EDirUse containds already E_Grid. It represents all the energy that does not go through the storage:

E_Avail = EDirUse + EBatCh

 

But is non correct! If the energy is sold to the grid it is not directly used;

[Bruno Wittmer]

This is a matter of definition.

'Direct Use' in this context just means that the energy did not go through the battery.

You can compute the energy that went directly from solar to self-consumption by subtracting E_Grid from this value.